1. Field of the Invention
This invention relates to tubular composite arc welding electrodes comprising a metallic outer sheath and a core within and enclosed by the sheath. More particularly, the invention relates to such electrodes balanced to deposit stainless steel weld metal, hereinafter referred to for convenience as tubular composite stainless steel electrodes, in which an improved core composition incorporating zirconium dioxide allows the electrodes to be used successfully in vertical up welding applications. My electrode is generally intended for gas-shielded semi-automatic arc welding, but with appropriate core modification within the scope of the invention it is also useful as a self-shielded electrode.
2. Description of the Prior Art
Many tubular composite arc welding electrodes have been developed for depositing stainless steel weld metal in automatic and semi-automatic welding processes. Such electrodes, whose popularity and acceptance is increasing, include those designed for gas-shielded arc welding, in which the welding arc is protected by gas supplied thereto from a source external to the electrode, and those known as self-shielded electrodes, in which components of the core provide arc shielding so that no external gas source is required. Examples of the former are the IN-FLUX* "G" wires produced and sold by Teledyne McKay, while examples of the latter are typified by U.S. Pat. No. 3,643,061, No. 4,149,063, and No. Re. 28,326. Although these and other tubular composite stainless steel electrodes provide sound, high quality weld deposits when used in the flat and horizontal positions, I am aware of none which can be used successfully in vertical up welding--i.e., where the weld metal is deposited in a vertical joint in an upward direction. In many cases the problem appears to be that the slags produced by such prior art in tubular composite stainless steel electrodes have relatively low melting points, such that in vertical up welding both the molten weld metal and the molten slag run or drip out of the weld joint. FNT *Registered trademark of Teledyne Industries, Inc.
Since many welds in stainless steel structures can be most conveniently and economically accomplished with vertical up welding, a tubular composite stainless steel electrode suitable for such applications would have significantly broader utility than the electrodes heretofore available.